It may have been Donald Trump’s most conventional move as president. During his holiday break at Mar-a-Lago in Florida, he convened meetings to start planning his reelection campaign.

Given the garish accounts in the new book by sometimes-reliable writer Michael Wolff — of Trump’s horror at winning in 2016, of his wife’s angry tears at the prospect of being first lady, of his lonely hours in bed with a cheeseburger, ranting at the TV — you might wonder why Trump would want a second term.

Rare is the president who doesn’t want one, despite the pressures and isolation of the job. Reelection is the ultimate ratification, the political equivalent of Sally Field’s 1984 Oscar moment: “The first time I didn’t feel it, but this time I feel it, and I can’t deny that you like me. You like me!”

Despite evidence to the contrary, Trump wants to be liked. So I don’t doubt that he’s laying plans for 2020, though a great many Democrats, some rival Republicans, and maybe special counsel Robert S. Mueller III have other plans in mind. When he schedules his next skull session, then, a certain topic ought to be on the agenda: timing the Trump Recession.

Yes, recession. I know this is one of those moments when people imagine the rules of economics have been suspended. The stock market races endlessly upward. Help-wanted signs paper shop windows. Economies around the world are in a rare period of simultaneous growth, and tax cuts have brightened corporate boardrooms from Portland, Maine, to Portland, Ore.

President Trump walks from the Oval Office. (Win Mcnamee/Getty Images)

But a downward turn lies somewhere ahead, be it a recession, slump or, God forbid, crash. A necessary part of the energy of economic cycles comes from the ebbing of each wave.

History suggests that the next recession is not far off. The current expansion, though relatively weak, has been steady since June 2009, making this the third-longest upward climb on record. Juiced by the tax cut, the United States is on track to record 107 months without a recession in April, passing the boom of the 1960s in duration. That will leave only the decade-long, 120-month run in the 1990s — when the end of the Cold War met the rise of the Internet to create a Golden Age for the U.S. economy — to be beaten.

In other words, just when the 2020 election begins to warm up, in spring 2019, the economy (if it isn’t already in recession) will break the existing record and begin testing the outer limits of the cycle. It’s not hard to imagine shocks that could trigger a drop. Democrats could win control of the House and ignite an impeachment crisis. Mueller’s investigation could take an unsettling turn. The Federal Reserve could raise interest rates faster than the economy can digest them. Or the opposite: The Fed could move too slowly and smoldering inflation could catch fire. China’s debt bubble could burst. North Korea could erupt. Or the very real threat, dreaded by Trump’s own economic advisers: The president could deliver on his trade war threats.

As the saying goes, it only takes one pin to burst a balloon.

Trump might ask George H.W. Bush what it’s like to have a recession arrive during a reelection campaign. The hero president of Operation Desert Storm, whose approval rating briefly reached 89 percent (even puppy videos aren’t that popular), lost 60 points in just 18 months. The mild recession of 1990 turned into a dogged job-killer, and though most economic indicators were blinking cheerfully by Election Day 1992, the damage was done. With help from H. Ross Perot, Bill Clinton made Bush a one-term president.

By delaying the inevitable, Trump’s tax cut may prove to be a double-edged sword. The recession that might have arrived in 2018 and passed like a summer storm will likely be shoved back a couple of years. If the piper presents his bill in the midst of Trump’s reelection campaign, the president better look out, because Democrats going back to John F. Kennedy score their wins when Republican presidents stumble into late-term economic woes.

Perhaps Trump should have followed Ronald Reagan’s example, accepting a recession early in his first term and trusting the recovery would come in time to lift him to reelection. That option is gone now. Having juiced the economy with tax cuts, Trump must either find a way to skim the froth — prod the Fed for rapid rate increases? unsettle the world with ill-advised trade wars? — or cross his fingers and power through. My prediction is that he’ll throw open the government’s liquor cabinets and pour out every stimulating drop he can get his hands on in a desperate effort to keep the party going through 2020.

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David Von Drehle writes a twice-weekly column for The Post. He was previously an editor-at-large for Time Magazine, and is the author of four books, including "Rise to Greatness: Abraham Lincoln and America’s Most Perilous Year" and "Triangle: The Fire That Changed America."